Enhanced adsorption of dye on magnetic Fe3O4 via HCl-assisted sonication pretreatment

Magnetic Fe3O4 particles, which are uniquely superior in separation and recyclability, are widely applied in environmental remediation. However, the limited diffusion of Fe3O4 particles in aqueous solutions leads to a low adsorption rate and available capacity. Thus, a novel and simple method to enhance the adsorption ability of Fe3O4 particles via HCl-assisted sonication was proposed. The Fe3O4 particles, pretreated via HCl-assisted sonication, were found to have a positive effect for the removal of C. I. Reactive Blue 194 from a weak acid solution. We characterized the sorption and desorption on pretreated Fe3O4 particles to understand its availability for dyeing waste water treatment. Sorption of dye to pretreated Fe3O4 particles was fast (adsorption could reach equilibrium in less than 40 min) in a wide pH range, and agreed well to the kinetics of pseudo-second-order and the Langmuir adsorption model. Meanwhile, after an effective regeneration with 0.1 M H2O2 solution and sonication for an hour, the pretreated Fe3O4 remains good adsorption activity which could remain the dye removal rate about 90% after five recycles. Thus, using pretreated Fe3O4, which has high adsorption efficiency and strong magnetic property, was an efficient and environment friendly method for dyeing waste water treatment.